7') 



THE AMERICAN NATURALIST [Vol. XLIII 



he freely acknowledges were the starting points of new 

 and constant races; and there is good reason to believe 

 that some of them occurred before the animals and plants 

 which underwent the sudden changes had been actually 

 brought under domestication or cultivation; in fact, that 

 the mutations themselves suggested to men the directions 

 in which their breeding operations should be conducted. 

 For example, take the case of the tumbler pigeon: Mr. 

 Darwin remarks concerning this that "no one would ever 

 have thought of teaching or probably could have taught, 

 the tumbler pigeon to tumble," 5 but it seems to me 

 obvious that no one would ever have thought of accumu- 

 lating slight variations in the direction of tumbling. It 

 is much more reasonable to suppose that the birds which 

 were artificially selected as the progenitors of the present 

 race of tumbler pigeons actually tumbled— that is to say, 

 they were mutants. As to the origin of domestic races 

 through modifications so abrupt as to have been thought 

 by Darwin entirely independent of selection, he gave it 

 as his judgment, as late as 1875, that 



It is certain that the Ancon and Mauchamp breeds of sheep, and almost 

 certain that the Niata cattle, turnspit and pu U '-d„<>. jumper and 

 frizzled fowls, short-faced tumbler pi-eons, hook-billed ducks, &c. 



has been wtth many cultivated plants. 9 



Now, considering, as I said a moment ago, that Mr. 

 Darwin's theory of the origin of species by means of 

 natural selection has for its main foundation-stones facts 

 derived from observation of the effects of man's selection 

 among domesticated animals and plants, -without which, 

 indeed, he admitted that he had no actual proof of the 

 operation of natural selection,— it is difficult to realize 

 the state of mind which led Mr. Darwin to add to the 

 sentence just quoted the following caution: 



